Oceanic regions have little or no radio voice coverage and radar surveillance to assist in air traffic control. Because of these communication difficulties and navigational inaccuracies, separation standards utilized by oceanic air traffic control for clearances must be very large. Aircraft may utilize a system called Automatic Dependent Surveillance-Broadcast (ADS-B) to broadcast information over a dedicated radio data link. The information may include current position, current attitude, category of the aircraft, airspeed, identification, and whether the aircraft is changing course (turning, climbing, or descending). Aircraft which utilize ADS-B may also have a display rendering positions of surrounding aircraft in the vicinity, which may be utilized to provide an Airborne Separation Assurance System (ASAS). The utilization of ASAS mitigates limitations in oceanic regions by allowing the aircraft to assume responsibility for monitoring separations between air traffic control-designated aircraft.
One application of ASAS is an In-Trail procedure (ITP). ITP allows an aircraft to transit through a flight level occupied by another aircraft at a much lower separation than the normal standard. This allows an aircraft to achieve a flight level where normal separation standards can be maintained by transiting through the intermediate flight level where it is not possible to maintain the normal separation standard. This enables more frequent flight level changes to optimal altitudes for better flight and fuel efficiency. Additionally, this enables improved safety by avoiding turbulent flight levels. Typically, the need to climb or descend is determined and potentially blocking aircraft at intermediate levels are checked for. If a potentially blocking aircraft is present at an intermediate level, compliance with ITP conditions is checked (referencing the potentially blocking aircraft). If ITP conditions are satisfied, clearance is then granted for the ITP. The aircraft then re-checks compliance and performs the ITP.
However, existing traffic displays do not visually present necessary information concerning vertical and horizontal traffic separation for an ITP. Thus, the pilot of the aircraft does not have clear and intuitive means of understanding the flying environment related to the performance of the ITP, decreasing situational awareness and complicating the ITP. Consequently, it would be desirable to provide a traffic display to visualize the vertical and horizontal traffic separation for an ITP.